The relationship between Mora-timed languages, long vowels and quantitative verse, also the status of Iranian and Balto-Slavo-Germanic?

Question

In an anthropological forum, there was once a view that because Latin, Greek, Sanskrit (also Celtic IIRC) are Mora-timed, they are divided into one subgroup. However, "syllable-timed" Iranian and "stress-timed" Balto-Slavo-Germanic are classified into another subgroup. That view also argues that languages may develop in the direction of Mora-Timed>Syllable-Timed>Stress-Timed, and Mora-Timed is closely related to long vowels.

However, we know that in the phylogenetic tree model, this is unlikely. First of all, Iranian languages (at least well-attested languages like Avestan, Persian, Pashto etc.) and Sanskrit must consist one certain subgroup. Secondly, the model that classifies Latin, Greek and Sanskrit into one subgroup, but Balto-Slavo-Germanic into another, except for one Schleicher's tree, most other trees are not like this. For example, in Thomas Olander's tree model, Italo-Celtic is the third to split after Anatolian and Tocharian, predating Germanic and Balto-Slavic.

Therefore, I have some doubts about the relationship between mora-timed languages, quantitative metre and long vowels.

1. First of all, are mora-timed and long vowels directly related? Many modern Romance languages have lost the opposition of long and short vowels in Latin and PIE, so they have become syllable-timed. But Proto-Iranian, Proto-Balto-Slavic, and Proto-Germanic all retain the opposition of long and short vowels. The following linguistic forum also recognizes that Lithuanian is a Mora-timed language, just like classical Latin, Greek, Sanskrit and Japanese. Therefore, in Balto-Slavo-Germanic, are there more Mora-timed languages (whether historical or modern)?

2. My second doubt is the relationship between Mora-timed and quantitative verse. According to Wikipedia, in addition to classical Latin, Greek, and Sanskrit, classical Persian, classical Arabic and Old Church Slavonic also use quantitative metre. However, Persian is a stress-timed language. On the contrary, although Japanese is a Mora-timed language, according to Britannica, Japanese often uses syllabic verse.

Answer 1

First, the division of languages into stress-timed, syllable-times and mora-timed is wishful thinking. Phonetic timing differences between languages are much richer than implied by this division.

Second, however, there is a difference between languages that distinguish heavy vs. light syllables (as opposed to ones where there is no phonological distinction). Amongst languages with a syllable-weight distinction, the primary distinction is between languages where long vowels and diphthongs define heavy syllables, versus languages where in addition coda consonants also define heavy syllables (and there can also be a distinctions in which consonants in the coda make a syllable heavy – sonorants, vs all consonants.

The concept "mora" is widely invoked as a device for making sense of this typology. First, it is presumed that the segmental concept "long" is to be represented with a distinctive mora (a vowel with two moras is long and a short vowel has only one; a long consonant has a mora and a short consonant has none). See Morén 1999 for discussion. That means that by definition, languages with long vowels have a moraic contrast. I suppose that the reasoning behind the claim about mora-timed vs. syllable-times languages relates to the historical loss of vowel length in parts of Indo-European. Retention of an old phonological feature is not evidence of a shared phonological innovation (that should be obvious) – perhaps the idea was that a change to syllable-timing (i.e. lack of moraic distinction in syllables) defines a historical innovation.

In those languages which make a distinction between heavy vs. light syllables, we find the following divisions. 1: There are long vowels, and only long vowels make syllables heavy. Coda consonants do not make a syllable heavy. 2: There are no long vowels, and only coda consonants can make a syllable heavy. 3: There are long vowels, and coda consonants make syllables heavy.

We generally simplify the analysis by saying that quantitative meter is based on distinguishing light vs heavy syllables, where a light syllable has one mora and a heavy syllable has two, but also noting that coda consonants can be moraic, perhaps by general rule ("all (sonorant) consonants in the coda are moraic").